In reinforced concrete construction applications, such as highways, or in floors, or in the walls of buildings, spacer devices, commonly referred to as chairs, are required for supporting and maintaining reinforcing rods or bars which are positioned in the area where the concrete is to be poured. These reinforcing rods are sometimes referred as "rebars". Depending on such parameters as the total surface area and the thickness of the end product of concrete, reinforcement is mandated in varying degrees by building codes. One such method of reinforcement involves a steel mesh, while in major concrete construction, such as highways, and for high-rise buildings, reinforcing rods of various diameters, typically one-half inch or more, are required. In addition, on such jobs, the reinforcing bars may be positioned in spaced layers due to the thickness of the floor, for example. In some installations, a first layer of rebar is provided, with the reinforcing rods or rebars in spaced parallel relation, that is, they are parallel to each other, and generally parallel to the surface on which the concrete is to be poured. A second layer of rebar is then added, with the orientation of the second layer perpendicular to the first layer, thus forming a grid or latticework. After the reinforcing bars or latticework is prepared, the concrete is then poured over this grid or framework, which is ultimately embedded within the highway, floor or wall.
By way of example, for a concrete floor on a prepared surface, spacers or chairs are utilized for providing the vertical separation of the rebar grid from the surface on which the concrete is to be poured. The prepared surface may be a wood or plywood structure or form, or may be a compacted surface, the latter of which may be provided with a layer of compacted sand, with a plastic sheet covering thereon providing a moisture barrier. Spacers or chairs are positioned on the prepared surface for supporting the rebars in a plane generally parallel to the prepared surface.
Such spacers are also utilized in forming walls, such as in the construction of buildings referred to as concrete tilt-up structures. With prior art metallic rebar chairs, after the wall is poured and sets, all spacer or chair locations are checked for exposure of any portion of the chair at the surface of the wall. All of such exposed metallic edges are ground and then sealed to protect from the formation of rust, which attacks the metal of the rebar or chair on the interior of the wall, causing structural weaknesses. In addition, in tilt-wall constructions, the metal from the chair can rust and eventually bleed into the concrete at the outer wall. This can create an unsightly and unprofessional appearance of the concrete structure. As such, a need has developed so as to protect such structures from the corroding chairs.
In the past, various U.S. patents have issued relating to such chair constructions. For example, U.S. Pat. No. 3,378,981 describes a chair having a flat base with a U-shaped metallic chair extending upwardly therefrom. The metallic chair has a pair of slots formed on the legs of the chair. The slots serve to receive mesh or rebar therein. The slots are oriented in opposed relationship.
U.S. Pat. No. 4,498,270, issued on Feb. 12, 1985 to R. J. Ilukowicz, describes a support for reinforcing rods or mesh. The support includes a plate of substantially planar construction. A cruciform structure is provided beneath and supporting the plate. The cruciform structure includes a plurality of legs and tips depending from the legs. The tips are adapted to expose a relatively minimal part of the structure with the support being embedded in a substance such as concrete. A structure is provided on the top of the plate to limit movement of the rod or mesh.
U.S. Pat. No. 4,835,933, issued on Jun. 6, 1989 to F. P. Yung, describes a spacer assembly with a body having a base portion with a generally centrally disposed support post portion. A clamp member is provided for simultaneously securing mutually perpendicular rebars to the chair. The clamp member includes a generally U-shaped lower portion. An arrangement of legs extend downwardly from the bottom portion of the spacer assembly so as to support the planar surface base portion thereabove.
It is an object of the present invention to provide a construction chair particularly adapted for use with tilt-wall construction.
It is another object of the present invention to provide a construction chair which minimizes the problem of rust associated with metallic chairs.
It is a further object of the present invention to provide a construction chair which minimizes exposure to the outside surface of the wall associated with tilt-wall construction.
It is still a further object of the present invention to provide a construction chair which is easy to use, easy to manufacture and relatively inexpensive.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.